From 9fe26e6dc90ce203f3be0a8ee0abf400668bde13 Mon Sep 17 00:00:00 2001
From: Geoff Berry <gberry@codeaurora.org>
Date: Fri, 22 Apr 2016 14:44:10 +0000
Subject: [MemorySSA] Fix bug in CachingMemorySSAWalker::invalidateInfo

Summary:
CachingMemorySSAWalker::invalidateInfo was using IsCall to determine
which cache map needed to be cleared of entries referring to the invalidated
MemoryAccess, but there could also be entries referring to it in the
other cache map (value entries, not key entries).  This change just
clears both tables to be conservatively correct.

Also add a verifyRemoved() function, called when expensive
checks (i.e. XDEBUG) are enabled to verify that the invalidated
MemoryAccess object is not referenced in any of the caches.

Reviewers: dberlin, george.burgess.iv

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D19388

llvm-svn: 267157
---
 llvm/lib/Transforms/Utils/MemorySSA.cpp | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

(limited to 'llvm/lib/Transforms/Utils/MemorySSA.cpp')

diff --git a/llvm/lib/Transforms/Utils/MemorySSA.cpp b/llvm/lib/Transforms/Utils/MemorySSA.cpp
index e873c9e4c04..90c23e1e144 100644
--- a/llvm/lib/Transforms/Utils/MemorySSA.cpp
+++ b/llvm/lib/Transforms/Utils/MemorySSA.cpp
@@ -799,19 +799,16 @@ void CachingMemorySSAWalker::invalidateInfo(MemoryAccess *MA) {
     if (!Q.IsCall)
       Q.StartingLoc = MemoryLocation::get(I);
     doCacheRemove(MA, Q, Q.StartingLoc);
-    return;
-  }
-  // If it is not a use, the best we can do right now is destroy the cache.
-  bool IsCall = false;
-
-  if (auto *MUD = dyn_cast<MemoryUseOrDef>(MA)) {
-    Instruction *I = MUD->getMemoryInst();
-    IsCall = bool(ImmutableCallSite(I));
-  }
-  if (IsCall)
+  } else {
+    // If it is not a use, the best we can do right now is destroy the cache.
     CachedUpwardsClobberingCall.clear();
-  else
     CachedUpwardsClobberingAccess.clear();
+  }
+
+#ifdef XDEBUG
+  // Run this only when expensive checks are enabled.
+  verifyRemoved(MA);
+#endif
 }
 
 void CachingMemorySSAWalker::doCacheRemove(const MemoryAccess *M,
@@ -1081,6 +1078,18 @@ CachingMemorySSAWalker::getClobberingMemoryAccess(const Instruction *I) {
   return Result;
 }
 
+// Verify that MA doesn't exist in any of the caches.
+void CachingMemorySSAWalker::verifyRemoved(MemoryAccess *MA) {
+#ifndef NDEBUG
+  for (auto &P : CachedUpwardsClobberingAccess)
+    assert(P.first.first != MA && P.second != MA &&
+           "Found removed MemoryAccess in cache.");
+  for (auto &P : CachedUpwardsClobberingCall)
+    assert(P.first != MA && P.second != MA &&
+           "Found removed MemoryAccess in cache.");
+#endif // !NDEBUG
+}
+
 MemoryAccess *
 DoNothingMemorySSAWalker::getClobberingMemoryAccess(const Instruction *I) {
   MemoryAccess *MA = MSSA->getMemoryAccess(I);
-- 
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